Refactor API structure: move chat functionality to v1 router, implement dependency injection for OpenAI client, and set up application state management

core/config.py

@@ -0,0 +1,7 @@
+from dotenv import load_dotenv
+from pathlib import Path
+import os
+
+load_dotenv(Path(__file__).resolve().parent.parent / ".env")
+
+DEEPSEEK_API_KEY = os.getenv("DEEPSEEK_API_KEY")